Problem Solving Forum

What is the effect of the wind-chill factor on the curing of epoxy and PU when temperatures are similar?

From
Tom Schwerdt of Texas Department of Transportation on
April 2, 2013: There is not really a simple answer. Faster airflow will allow faster solvent evaporation and more rapid initial set. With solvent out of the way, actual curing should move along moderately faster., and significantly faster in the case of some epoxies with ketone solvents. (The curing agent would be partially or fully tied up as a ketamine until the solvent is gone.) Thermal mass of the substrate (in most circumstances) should keep the coating temperature pretty close to ambient. One possible confounding factor for polyurethanes: higher wind speed will bring more ambient moisture in contact with the PU, possibly reacting with the isocyanate.

From
Carl Thompson of Hill Brothers on
April 1, 2013: Any organic reaction is slower with a wind chill factor, even though temperatures are the same.

From
Tom Koep of Coatings Unlimited Inc. on
April 1, 2013:NONE

From
Jay Barstow of Aeroflor Coating Services on
April 1, 2013: This is a trick question ... unless there is something to evaporate, temperature is temperature (though air flow could accelerate temperature drop to ambient, but in a thin film that really wouldn't be a factor). Solventless epoxy and urethane? No change. I suppose a solvent flash due to air flow could lead to a surface cure of a solvented product and the resultant entrapment of solvents. An ambient of 50 or so will effectively stop the curing process, but this isn't a "wind chill" effect. Sooooo ... April fools?!?

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